A Journal of Impossible Things
by WordShark
Summary: There once was a human, an army doctor, who lived with another very brilliant human in a flat in London. One day they had a falling out, and on that day, the doctor met a very brilliant alien who also called himself a doctor. They saved the world. A lot.
1. Chapter 1

They all had different explanations for what happened.

Lestrade was sure that everything had started with the newest grotesque murders. Mrs. Hudson believed that it had to be something about camaraderie within the medical profession. Mycroft assumed it was founded in John's adrenaline addiction. Sherlock rejected all of these half-baked ideas, insisted that John had nothing to do with it, that everything had changed when the other lodger moved in, barreled into their lives and _disrupted_ things.

John, though, knew that it began with Sherlock.

He had woken up to the sounds of clatter and the smell of smoke, but he hadn't moved. For a few moments, he let his eyes adjust to the soft, dull light playing across the ceiling, pupils dilating and contracting minutely. Letting himself actually wake up, if only so that he could be alert enough to save his lunatic flatmate from an untimely end, again. _If he wanted to be saved_— he suppressed the thought, even as his throat constricted. A few moments passed. Something crashed to the floor downstairs. John could feel all of his age resting deep in his bones, in the lines of his face and the pit of his stomach, the weight of inevitability pulling him into the mattress. It was a feeling he'd thought he'd left behind, back in Before Sherlock. A feeling of steady suffocation, sinking. Sagging.

He fought against it, levering himself up onto his elbows, a slight crease between his brows as his shoulder ached and his leg twinged. The furrow deepened, the only sign of discomfort he would allow himself. It was a psychosomatic injury, and he'd be damned if he'd let his insecurities play his body like this. _Sticks and stones,_ he thought wryly and swung his legs over the side of the mattress, letting his feet brush against the cold wooden floor. He couldn't hide in here, though he knew that the chill that awaited him outside his door would cut him to the quick, aggravate him, and make his life a wretched state of affairs. And he would _not_ take his cane, he thought, a spurt of defiance shooting through him, making him tilt his head back and stretch his muscles (or was it just obstinance?). He was not too— He didn't let himself finish the sentence, but landed on his feet solidly, ready to face whatever was thrown at him that day.

By the time he had come downstairs, Sherlock had already disappeared. John felt the cold pierce through his jumper; settle into his skin, and shook himself. After what he had seen last night, it wasn't surprising that Sherlock didn't want his company. He winced as he moved to get a cup of tea and felt his leg throb with _imaginary_ pain. It wasn't like he hadn't been dismissed before, but this. This was new.

John had known that his flatmate was in a foul mood by the time they returned from the crime scene: something had escaped his all-seeing eyes, something that he insisted was right there. "It's there, somewhere in front of me, I can almost— and then it isn't! What _does_ that, that's not possible!" He simply shrugged and placed the journal he had bought to keep observations in on the living room table. A second opinion, Sherlock had said, helped him, so— But it quickly became apparent that he had overstepped his bounds. After many hours silent meditation, Sherlock spoke. "Here," he stated flatly, waving a hand at the journal John had left open for him. "I don't need your notes."

John glanced up, suddenly unsure. "Sorry? But I thought you said I ought to get a notebook for—"

"Not necessary." It was like the rug was being snuck, rather than yanked, from below his feet. He gaped at his flatmate for a few seconds, then pursed his lips. What was Sherlock up to?

"You wanted a second pair of eyes. This is what I saw."

"And I'm saying I don't need them, must I really repeat myself?" Sherlock drawled, voice cool. "I have everything I need already." John nodded, a little lost, and tried to return to his paper, when the low voice continued. "You ought to go into work tomorrow."

He scoffed then, _sure_ that his friend must be having him on. "Pardon? And get interrupted halfway through an examination by irate texts about how sick people can't possibly be more interesting than a corpse?" Sherlock waved his hand again, not even turning to look at John.

"You ought to be doing what you're _best_ _at_." The words were calm, precise, with meaningful emphasis on the last words.

"Not helping you out then?" Sherlock's gaze, when it turned on him, was appraising— mocking. _Bored._ It spoke volumes. It _hurt._ "Right then," he muttered, flushing and getting up, moving off upstairs before he raised his voice, let some of the hot fury boiling in his veins burst past his lips. He refused to get into another argument where he'd yell and Sherlock watched him with that same chilly gaze as he dismantled every argument. The anger kept him awake, kept him growling under his breath and punching the pillow, but the thing that made his hand tremble and his leg ache was the knowledge that for some reason he had started being treated like just a member of the Yard.

John's phone buzzed and his hand jumped to his pocket with perhaps more alacrity than he wanted to admit. _Speaking of the police_, he thought, an ironic smile quirking across his lips as he saw Lestrade's name on the display. It disappeared immediately, however, when he finally moved into the kitchen and saw what had been "experimented on." "Dammit, Sherlock!"

"Of everything you could possibly destroy in the flat, you go for sugar bowl, the stove, and the kettle?" John hissed as he and Sherlock moved down one of the stark hallways that led to Bart's laboratory, noticing to his annoyance that the other man lengthened his stride. "Are you just out to sabotage me now?"

Sherlock sighed through his nose, glancing down at the shorter man, and John was forcibly reminded of Mycroft's look of condescension and indulgence. "So Lestrade's got you at his beck and call now? Nice to see he hasn't run out of lap dogs. Or was it my brother?" He felt the breath catch in his throat and swallowed, hard. He did _not_ need to deal with this— despite what everyone believed, he was not "stuck" with Sherlock, and there'd be no taking pity on Lestrade from now on.

"It was Lestrade, and I only came because he sounded frantic. Anderson refused to work with you." He nodded to himself grimly. Before, he'd have laughed. Right now, it was hard not to sympathize. "I'm just supposed to do what we— what I usually do. I didn't even get to say hello to the new lodger." John did feel sorry that he hadn't been given time to talk to the new tenant in 221C; according to Mrs. Hudson, he was a doctor of some sort. Odd, very odd. A traveling man, she had said knowledgably, "And when I told him you were an army doctor, he mentioned being in a war himself one time! I think the two of you will have lots to talk about— someone with similar interests." It would be nice to have a conversation, John thought, instead of being talked _at_. And if anything, he could have warned the poor bloke about the violin, gunshots, yelling, and police charging up and down the stairs at all hours.

"Yes, well, he won't be staying long." John peered up at Sherlock, scowling.

"And why not?"

"Older man living alone who's seen war and has traveled often, now looking to settle down?" Suddenly those cold grey eyes were fixing him with a steady, deliberate look. "I doubt he'd stay in 221. It's a bit frenetic for someone of that disposition." John knew exactly what he meant.

"Yes, he'd have be a bloody fool to stick around, wouldn't he?" he said, voice a bit louder than he'd have liked. Sherlock merely looked away and walked through the doors to the lab, calling imperiously for Molly. John stopped short in front of them, practically shaking with rage, eyes fixed sightlessly on the small, rectangular windows. Right. He didn't have to stay here. He didn't have to be here, he wasn't on the damn payroll. Anderson would have to grow a spine, because _he_ was, and he wasn't going to stand for it any longer. Any of this. "Sociopaths get bored," he muttered to himself, and turned on his heel. He'd been a fool to think he was some sort of exception.

John had every intention of going back to the flat, calling Sarah, and seeing how long she was willing to put up with him— hopefully long enough for him to calm down, or for Sherlock to… No, that wouldn't work. He'd just have to see what happened. But as he passed the windows that looked down into the mortuary, he came to an abrupt halt.

The was a stranger in the morgue. This struck him particularly because how often did he get to think "There is a stranger in my morgue"? The body he recognized, it was the one they had looked at just last week, but the person in there was definitely a stranger. A strange-looking stranger at that… John squared his shoulders, scowled down at the interloper, and, banging the door open, marched down the short flight of stairs that led to the mortuary. "And just _what!_ do you think you're doing?" he barked out as he banged open the second door, and was gratified to see the other man jump and turn around to face him, a suitably guilty look on his face. His very unusual face, John thought, as he watched the expressions flit across it— worry, more guilt, bewilderment, a sort of attempt at explanation, and then a sudden, brilliant look of realization and excitement.

"Hello!" the stranger shot back, his voice as young as his appearance. He waved. He bounced on the balls of his feet. He looked utterly pleased with himself. "I'm the doctor— and you're my _neighbor!_"

"I'm your—" But the other man was already by his side, clasping him gently by the upper arms and leaning forward. John's eyes widened exponentially. He leant back, keeping his eyes fixed on this bizarre person and balling his fists. He tried very hard not to yell again. The stranger had pursed his lips and was beginning what looked like an air kiss, but paused at the expression on John's face and seemed a bit uncertain.

"This is what they do nowadays, isn't it? It seemed to work before but you're a bit, er, _intimidating_, so perhaps a handshake is— yes that's much better!" He moved away, gripping his hand firmly and beaming again. "Of course, an army doctor wouldn't want anyone intruding on his personal space, I suppose I should have known but who has time for remembering things like that? A great distraction from much more important things _liiiiike_ the body over there." He spun around again, pulling John after him, his entire frame buzzing with energy.

"See, there's something wrong with this corpse, isn't there—?" The stranger bent over the corpse, which was mutilated beyond belief. _Well, her chest is caved in,_ John thought, but before he could say anything, the other man had plowed on, poking the body and pressing at its temples. "Something not _quite_ right. Do you notice it? You do, of course you do, but rather you don't, can almost see it and then— poof, it's gone again, lurking in the _corner of your eye._" He pulled John around the edge of the table, peering down into the dead girl's eyes. Bowtie, floppy hair, tweed suit; he seemed like some escaped junior academic on the lam from his professors, full up with knowledge and energy and not much else. "You see, there— there!" The stranger spun John around, making him splutter, so that he was parallel with the slab, then locked eyes with the doctor. His eyes were dark, very dark and grey, like storm clouds, and when they were trained on him, John found he could not look away. "This thing that I am looking for, this thing you can't see yet, it's there," the stranger continued quietly. "Corner of your eye: most things hide there and they don't like to be disturbed…"

The door opened suddenly, and Lestrade and Sherlock strode inside, already arguing furiously. John dimly registered that they were yelling about him, but his attention was still captured by the man who had released his shoulders and who was now smiling at him. A secretive smile, full of bizarre camaraderie and mischief. "I suppose I'll see you back at the flat, Dr. Watson," he murmured, and before Sherlock had even looked around, the stranger was gone.


	2. Chapter 2

"Who was it?"

John pretended not to hear Sherlock, shifting slightly in his seat. The consulting detective had descended upon the corpse with an almost desperate eagerness. Or, at least, it would have struck John as such if he weren't wandering around the morgue in a daze. _What just happened?_ he found himself wondering, remembering how the stranger seemed to draw John in with his eyes. It was rather as if he had been held underwater, all that energy concentrated on him, and then had abruptly been allowed to surface, gasping for air. Sherlock rattled off facts about the victim— the well-formed callus on the side of her left thumb meant she was a cellist, probably attended university on a scholarship, going by her second-hand coat and good, but old, shoes— but when asked to describe the murderer, he fell silent. The cause of death was clear: someone had bashed in her chest with a very large rock, then gone on to mutilate her cheeks and lips. But the question of the culprit was impossible to answer, apparently. No one could cut open their own mouth _after_ they were dead.

Sherlock gave a low hum of disapproval, his feline gaze moving from the cab window to John's face. "I see. You're angry with me, so you'll indulge in giving me the 'silent treatment.' I was told I was the immature one in this relationship…"

"Well you are," John shot back. "Who over the age of six would treat his friend like dirt just because _he_ hadn't gotten what he wanted?" He thought he saw something change in Sherlock's expression; what was haughty before suddenly seemed lost and rather—frightened. It disappeared immediately, but the moment of vulnerability shone like a spotlight in John's mind. He might not be as observant as a consulting detective, but he could read every nuance of his friend's body language. _Maybe it's just a matter of what you pay attention to_, John's unhelpful mind supplied. Dismissing this quickly, he turned himself to face Sherlock. "Alright." His tone was put-upon, but a smile lurked in the corners of his lips. "I wasn't alone. How'd you know?"

A ghost of an answering smile crossed Sherlock's face. "You never go into the morgue without a reason; I assume something about the fact that the people inside can no longer be saved bothers you. When you're with _me_—" John noted the emphasis, a small shoot of pleasure blossoming deep inside "—your sense of 'doing justice' is fulfilled. But you weren't on the case at the time." Sherlock scowled. "You were, I think, heading to Sarah's to 'get some air.'"

John couldn't help the chuckle that burst from his lips at this, but stifled it, nodding to Sherlock to continue. "Something must have distracted you on your way back from the lab. Bodies don't usually open their own morgue drawers, and when Lestrade and I arrived, you weren't inspecting her corpse. You were standing next to it, staring up at the space the other person had just vacated." He frowned slightly. "Medium height, then."

Suddenly Sherlock scooted to the edge of his seat and leaned across, ignoring John's cry as his personal space was invaded for the second time that day. "There is a slight smell of old tweed mixed with odor of odd perspiration." Sherlock narrowed his eyes, analyzing every scent, and for a brief moment (in which every one of John Watson's muscles seized) pressed his nose into the fabric of John's jumper. "Most likely a male, but not a doctor," he continued, pulling back. "A stranger."

He couldn't help it. John cracked a grin, trying not to laugh a bit hysterically. The other man glared. "What?"

"Wrong on two counts: he was definitely a doctor, though I doubt he's ever worked at Bart's. And he's not a stranger, not really—he's our new lodger!"

Their new lodger was not at 221C when they returned, however, and the door to his flat was locked. John managed to persuade Sherlock to leave off trying to break in, though he suspected that the other man would make another attempt later, when he thought John wouldn't be expecting it. When he mentioned the case, however, his friend shut down, all the openness of the cab ride disappearing into brooding silence. John couldn't help but feel angry— he had gone back to being no better than the skull on the mantelpiece. Worse, in fact, because at least Sherlock would consider talking to the skull. He was concealing things…

Sherlock had kept the fact that he was meeting Moriarty a secret, hadn't told John about the near-death encounter he'd had in Soo-Lin's flat (he'd found out much later; the argument had been explosive), and had allowed a serial killer cabbie to drive him someplace secluded for a deadly game of wits without a word to anyone. The more John thought about it, the less certain he was that Sherlock needed him. He almost felt like an aberration in the other man's life, something that could leave as easily as it came. The thought made his entire body ache.

Several hours of silence later, John was drinking his third cup of tea and reviewing the notes Sherlock continued to reject. Something important was wrong here, but just like before, he couldn't put his finger on it. _"No trauma to the head at all—skull intact. Seems odd that a killing blow with a blunt object would not be delivered to the head."_ He leaned back, frowning. The fact had occurred to him later, when he had been riding in the cab. Not at the time, of course; not in the hospital. But why? What was it about the body that made it difficult to— well, to _see?_ He could remember Sherlock's angry rant from the day before clearly: _"It's there, somewhere in front of me, I can almost— and then it isn't! What does that, that's not possible!"_ The furrow in his brow deepened. What had the doctor said about the corner of his eye? That things hid there, not quite seen, out of sight. "Out of sight, out of mind," John murmured.

His head jerked up. His eyes widened. "_Oh._"

He jumped to his feet and marched briskly to his laptop, ignoring the puzzled looks Sherlock was giving him. Quickly typing "parasites" into Google, John scrolled through the results quickly, head spinning with his sudden epiphany. Something was _in the minds _of the corpses, something hiding in their skulls. It sounded ludicrous, bizarre, stupid; he was assuming far too much, acting on guesswork and shoddy observation; but he couldn't let go of the certainty that had settled in his chest, heavy and solid. Sure enough, there were plenty of bugs that ate into their victims brains, lived inside the bodies until they were full-grown, and the discovery sent another wave of elation coursing through him. _So this is what it's like to be a Holmes_, John thought rather giddily, letting a broad smile spread across his face. He stood again, snapping the computer shut with a quiet _click_, and dashed upstairs. He didn't need Sherlock to investigate this little theory— and doubted he could handle being proven wrong in front of his friend. Tugging open the drawer on his nightstand, he pulled out his Browning and slid it into the waistband of his jeans, rushing back downstairs to grab his jacket. "Don't wait up!" he called back, filled with equal parts excitement and fear as he considered what he would find lurking behind the sightless eyes of Ms. Christine McCully, five foot two student cellist.

When the cab pulled up to Bart's again, twilight had fallen. John went to the desk to explain that he was with Sherlock Holmes, helping to investigate official police business, but the guard on the other side simply waved him through. He raised his eyebrows in surprise, but took the opportunity, setting off down the hallways at a brisk trot. Soon, he found himself approaching the same long windows from before. The morgue was brightly lit, compliments of the guy behind the desk, and he could see that nothing had been disturbed. Somehow, this didn't seem like much of a comfort; John had almost hoped that the bizarre doctor from before would be there with him. His adventures didn't usually consist of him sneaking through eerily silent morgues by himself in order to examine a mutilated body. And it really was eerie, the way the florescent lights made the immaculately clean tiles gleam. How it threw the spaces by the cabinets into deep shadow. Very creepy.

And then there was the feeling that he _wasn't_ by himself. That he was being watched.

It wasn't as overwhelming as when, immediately after John had been informed that Mycroft had them at Level 8 surveillance, a strange man bumped into him on the street and said, in an undertone, "Do remember to lock the front door, Doctor Watson," but it was _there._ And it was insistent.

John opened the door to the mortuary as softly as he could, though why he did so was uncertain, even to himself. No one was here. That he could see— _No, stop thinking like that_, he chided himself mentally. _That won't help you_. Straightening his shoulders, he fell into his marching stance and strode over to the drawers. "Just open it. Easy," he muttered to himself, summoning his courage. Grasping the handle firmly and feeling the slow twist of anticipation in his stomach; the tension cording in his muscles as he pulled the door open; the prickle that ran up his spine as he saw the woman's mutilated face. Slowly, he turned away…

Even more slowly, he tilted his head towards the body, eyes sliding to the place no one _ever_ wants to look.

Nothing was there.

The breath he'd been holding caught in his throat and John frowned, brow contracting. Nothing in the eyes, nothing at all. But— He tilted his head, craning his neck forward to get a closer look at the hands which had fallen from out from under the sheet. They seemed to have opened up at the fingertips, letting forth stems of something silvery. Like a strange new plants had pushed back the skin and muscles of the dead woman and had grown out along the phalanges. "That's not something you see every day," John murmured to himself, crouching to get a better look; it was a grotesque maze of intertwined vines— or were they roots? Because they seemed to have been reaching out, down, searching for something. Sustenance? But that made even less sense; if anything, they should have been getting their nutrients from the dead body….

Suddenly, John realized what he was doing. Emitting a loud, shocked gasp, he started backward. He had just been examining a corpse that appeared to have _things_ growing out of it. Things that had no place in a body, much less a murdered one that had shown no signs of infection or infestation during the autopsy. "Holy Christ," he muttered, blood draining from his cheeks. Something had been _living_ inside this body, undetected by not only an entire forensics team but _Sherlock Holmes_. "Okay." John drew a deep breath, trying not to notice how hard he was shaking, ignoring how much he _really_ wanted to run out of the room. "The parasite theory is looking good, at least. But, what is it? And—" he forced himself to step forward again "— what is it doing here? In a body that's already dead?" Slowly, shuddering slightly as he did so, John lifted the sheet a little farther and gagged. White vines burst from the woman's chest cavity, all traveling down and out, _reaching—_

"Excuse me? Dr. Watson?" John whirled about, hand automatically reaching for the gun in his waistband. It was only the security guard. "I'm sorry, Doctor, but I called the inspector. He doesn't think it's such a good idea for you to be down here, not without a police officer accompanying you." The man gave him an apologetic grin, not shifting from the doorway. John's shoulders sagged with a mixture of relief and disappointment.

"Actually, can you phone Lestrade again?" he asked, in a tone that was nearly a command. "There's something here that I think he ought to see." The guard frowned and stood on his tiptoes, leaning around John to see it. John stepped back, turning to look at the cadaver again. "Honestly, you might want to see this yourself."

"That's okay, Doctor Watson, I'll stay right here," the other man said, and John's mouth twisted into a wry smile. "But really, sir, I need you to leave now."

"Why'd you let me come in in the first place then?" John muttered, trying not to retch as he looked over the woman's split open shell. For a second, there was complete silence behind him. His brow twitched downwards. His skin prickled. Something wasn't right…he began to turn his head—

"Because no one else can see this," said a voice, directly by his ear. Giving a loud shout, John spun about again. The security guard was standing just behind him, and his eyes were swollen, _writhing_ with the things inside them. A few strange, sliding motions, and he was raising his hand, jaw dropping open at a hideous angle as the vines split open his palm, writhing towards John, who scrambled back and slammed into the body drawer, swearing at the top of his lungs. The creatures inside the guard's body were blossoming, bubbling with spores, dark grey masses that were trembling on the edge of the tendrils, almost as if they were about to shoot towards him— shoot. _Shoot!_

In one swift movement, John had straightened, pulled his gun from his waistband, and shot the guard between the eyes. His head exploded in a mess of blood and silvery fluid, brains covering the floor like a disgusting carpet pattern. Breathing hard, John watched as the creatures on the tile writhed, almost as if they were in pain. He couldn't summon much more than grim satisfaction at the sight, until he realized that they weren't twisting about in agony. They were wriggling towards him. "Dammit!" he growled through his teeth, backing away again and checking his magazine hurriedly. This was not how he wanted to die, as food for parasitic worms.

"I don't think that you have enough bullets to take out all those vines." John's head jerked about. The odd fellow from before was standing next to him, leaning on the other sets of drawers with his eyebrows raised. John's expression contorted into one of complete confusion. "I've always said guns are nasty: they give species a really easy way to kill each other, and they're never as helpful as they need to be." The stranger stood up, straightened his tweed suit, and whipped out a strange, coppery cylinder with a green light on the end, pointing it confidently at the creatures slithering in their direction. The noise it emitted was just as bizarre; high pitched, almost painfully so, and John spun back around to see the things actually curl in on themselves.

"A dog whistle for deadly parasites?" he said, a little breathlessly. The stranger raised his eyebrows at John. "What sort of a doctor needs that?" The man paused, frowned, then grinned widely.

"A multi-tasker! And Dr. Watson, I'm not _a_ doctor." The grin expanded. "I'm _the_ Doctor. Emphasis on capitals."


	3. Chapter 3

"What does that even mean!" John shouted as he and the newly-named Doctor ran pell-mell down the hall, the other man turning on his heel to send another burst of sound at the door that swung shut behind them. "How can you be _the_ Doctor? The Doctor of what?"

"Of— of everything! I don't think this is the best time to ask for my credentials!" The stranger yelled back, shooting John a look. "Come on!" He grabbed the ex-medic's wrist and dragged him up the stairs, running directly to the lobby and pointing the cylinder at the telephone, which began ringing loudly. He snatched it up and released John's arm, spinning around to face the desk. "Hello? Chief Inspector Lestrade? Your morgue is currently experiencing a minor— errr, major infestation of…" He looked towards John, who stood watching him, frowning, arms folded. Apparently understanding that he was getting no help from that quarter, he turned back around. "An infestation of _taikreng unilatero_, intergalactic spores with the perfect method of asexual reproduction and a sure-fire way of surviving that only requires that everyone else on the planet die— you know what? Too much for a phone call. We'll just call them The Nasties." He paused, raising his eyebrows at John again. "You've got _lots._"

John rubbed his eyes. Who was this guy? He just showed up and saved John, then proceeded to act like an idiot over the phone, sounding like a madcap child breaking into the hospital. "Here," he commanded, holding out his hand abruptly. The Doctor looked at him, surprised. "Give it to me, he'll listen to me." The eyebrows did not lower a nanometer, but the man handed John the receiver. Sighing audibly, he took it and held it to his ear, just in time to hear Lestrade exclaim, "What the _hell_ are you on about?"

"Lestrade," he said, as calmly as he could while watching a grown man in a tweed suit dance to a door and look through its window to check on creatures that wanted to bring about their immediate demise. "It's John Watson."

"Oh god— you've been abducted again, haven't you?" Lestrade, to John's amusement, sounded genuinely anxious. Though he couldn't blame the man; his track record for the past month or so had not been good. "How crazy is this one?"

"Err… He's not really dangerous. He kind of saved me," John said, looking over his shoulder at the strange fellow, who was now— adjusting the pitch on his cylinder? "Just in case, the guard's desk has extra handcuffs, right?"

"Yes, but—"

"Good. Don't bring a lot of people here, I'm still not sure what we're dealing with. Bring Sherlock." And with that, John tugged open the desk drawer and pulled out extra cuffs before setting the phone down decisively. Instantly, the Doctor was his side, grinning wildly; John couldn't help leaning back a little. _Don't use your gun unless it's absolutely necessary._

"You are _very_ good, you are spot on, yes— keeping the whole thing contained, quarantined. Brilliant!" _There are no eyebrows on this face, how is it so expressive_, was all that John could manage to pull together out of the sea of confused thoughts he was sinking in. "You made a wonderful medic, didn't you? Yes I can see it, _triage_, always thinking of who you can actually save. Not just who you wish you could. Including yourself." Somehow during this monologue, his manic speech had slowed down to something much more knowing, calculating, and the look in his eyes was fond. And this was a bit too much for John (a bit too much like Mycroft reading out his life's details in that paternal voice).

In an instant, he had the Doctor facedown against the desktop, protesting loudly as his arms were twisted around and cuffed behind his back. "What is it with all of you and handcuffs? Do I have a face that people see and think 'God, lock him up quick?'" John rolled his eyes and turned the other man around, sitting him squarely in the guard's chair and, to his displeasure, on top of his cuffed hands.

"It's more the way you act," John said, fixing his gaze on the Doctor's face and crossing his arms again. "Who are you? What are you doing here? How did you know about those things?" Seconds later, he regretted locking eyes with the man. There it was again: the feeling like he was being sucked into the Doctor's pupils, drawn deep into his mind, weighed down the intensity of his stare. As if all the energy in the universe was focused on him, trying to make him _see._

"I'm here because I've been looking for a creature, a very dangerous and ancient race that has the power to wipe out all of humanity through sheer determination and hunger. It needs a home and it's chosen your planet. I know this because this is what I _do_. I'm the Doctor. I try to fix things, and it doesn't always work but I'm trying very hard to make this right and to do that, John, I need you to uncuff me. Because the future of not only one, but two species depends on this, these few seconds where I tell you that we're running out of time and you _believe me. _You believe me because you've been in my position before." His eyes remained locked on John's unblinking, steady, and he was almost pleading, but mostly just telling because John did understand, deep down. "And you know you'll need all the help you can get."

—

A few minutes later, when the police arrived, they were both uncuffed and staring through the tiny glass windows. "The taikreng are a tricky species; they're perfectly capable of hiding in plain sight, thanks to a sort of built in perception filter, but what they really are good at is walking their victims around, treating them like big flesh suits— Big flesh suits that they eat from the inside." John's expression was horrorstruck, and the Doctor looked a bit guilty at being the cause. "Yes, well, there's a reason that they're considered intergalactic menaces."

"And you do what— hunt them?" John asked in a low voice, face twisting even more as the vines attempted to climb the other side of the door. He supposed it might be a beautiful sight, these creatures spreading like thin silver wires through the hospital, if he weren't so worried about becoming a human jumpsuit.

"Er, well, no," the Doctor replied, frowning. "I mean, that's one way to look at it but it's…limited. I mean, there's more than one species involved here, it's much more complicated than pest extermination." John frown mirrored the other man's. He opened his mouth to protest, only to be cut off by the Doctor. "The taikreng are considered criminals by other species, yes, but in the way that the Romani are considered criminals on Earth. They're nomadic and they tend to infest bipedal animals, which can decimate livestock or a homepeople. Like yours." He surveyed the vines— no, the animals?— that were spreading themselves across the floor of the hospital and seriousness descended upon his features like a physical weight. John suddenly saw a much older man standing before him.

"They need a home." It wasn't a question. "What happened to theirs?" The Doctor, his face still turned to the door, didn't reply. In that moment, the doors to the floor slammed open, causing both of them to turn— the Doctor quickly placed the cylinder back in his coat pocket. Lestrade and Donovan strode into the room, guns drawn, the pair of them closely followed by Anderson and a few other members of the forensics team. John could see, in his peripheral vision, the Doctor's expressions change faster than a chameleon's colors. Surprise, approval, anxiety, and, finally, bright, excited happiness. Confidence.

"Hello gentlemen! Ladies. Members of the Metropolitan police! My name is Doctor Smith and—" Donovan stepped forward, pulled his flapping hands out of the air, and cuffed their wrists together in a series of swift motions. "What? I— _What?_" The Doctor's jaw dropped. He turned outraged eyes towards John, whose eyebrows had hiked high into his hairline.

"Er, Donovan—"

"The maniac's been restrained, sir," she said briskly, looking over her shoulder at Lestrade, who still had his gun trained on the Doctor. The detective inspector gave a curt nod to his second in command and began examining John's expression.

"Are you alright? Sherlock's on his way right now."

"Yeah, listen— Lestrade, you really don't have to do this—" Mortification colored John's cheeks a light pink; he could see the Doctor angrily trying to bite through the links of his handcuffs.

"Sure, right. Last time you and Sherlock almost got yourselves killed, I got an angry message from the _government_ about not doing my job right." Still, Lestrade lowered his weapon, his eyes trained on John's face. "Sorry that restraining madmen is part of my job."

"That's the problem, I don't think he's actually—"

"How long have you been breaking into Bart's, then?" Anderson's voice was cool and sneering. John rounded on the man, only to see him addressing the Doctor, who was now trying to reach into his inside pocket with both hands. "Because we've had trouble with people messing with us before, and we're never very happy when it happens." _Messing with us? Does he mean Moriarty, when he attacked me and Sherlock?_ John wondered, unsure of how to react. "All of the bodies keep being amputated or stolen!" _Ah. Not exactly._

"Excuse me!" John interjected forcefully, before the Doctor could start protesting (and Anderson could put two and two together). "I'm pretty sure he's not a trespasser! He wasn't lying about the things he was talking about, the— taikreng. They're out there, and he just risked his life saving mine." There was a long pause, and all eyes swiveled towards the stranger as John continued. "I think we owe him our respect, as well as our attention." John saw the Doctor watching him over the crowd of policemen, his dark eyes fixed on John's face, their expression warm.

"Quite right!" The stranger's voice broke through the silence that followed John's remarks, tossing his hair out of his eyes and smiling thinly at Anderson. "Dr. Watson, if you don't mind helping me reach it, there's an identification card in my inside jacket pocket. I'm sure it'll clear this all right up." John sighed and marched over to the man, giving him a look that obviously asked if this was necessary. All he received in return was a sly smile. Grumbling a little about hapless geniuses, he dug his hand into the right-hand side of the tweed suit— and froze. Thumping away under the shirt pressed against the back of his hand, John could feel a heart. A _heart._ Immediately, he moved his hand to the other side and started visibly, staring up into the Doctor's smug grin. _Two hearts?_ "That's the right pocket, Dr. Watson. Inside left, yes! That's right, o-_kay_."

Flicking the small cover open, the Doctor held up credentials which, even in his dazed state, John could see were brand-new, signed by the Surgeon General himself, and told everyone in the room that this bizarre person— _with two hearts!_— was Doctor Jonathon Smith, of the Investigative Science Bureau, specialty strange parasites. "I think that's all the information you need!" Lestrade's eyes grew wide and apologetic and Donovan stepped forward quickly, unlocking the fellow without a single word. Spinning on his heel, Dr. Smith winked at John before grabbing Donovan's, Andersons', and Lestrade's hands in turn and pumping them eagerly. "Metropolitan Police, Scotland Yard, whatever name you fellows take, it's always a pleasure and an honor to work with you. Honestly! Some of the best minds in here, all working for justice." He looked over his shoulder at the window behind him, frowning. "Unfortunately, justice isn't what we're dealing with, but an extra bunch of hands is wonderful to have!"

"What, to go with your extra heart?" John muttered, a bit hysterically. The Doctor looked to him and frowned; the ex-medic was looking rather overwhelmed. Excusing the pair of them, he pulled John to the side, but then clearly wasn't sure how to proceed. "You have another heart. How did you get that? What _are_ you? That's not— you're not human!"

"John, you're panicking. This isn't half as bad as it seems—"

"No! no, it's fine, you being… It's fine," John muttered, glancing about to see if anyone had heard his outburst, before looking back up at the Doctor. "Really. It— it explains a lot. Like the dog whistle." He paused. "…And the fact that you even know about those things. It, um. It just took me by surprise."

The Doctor leaned closer to him, inspecting his expression; John leaned back a little. "Are you sure you're alright?" the man asked slowly. "It's okay for you to be freaked out by this." John nodded, gulping a little bit. Did this bloke have extra teeth or— or wings? What sort of a person was he? Was he from space? the future? John suppressed the questions, he shut them down, clenching his jaw to keep them from spilling out. Now was not the time.

"Later." John let himself smile a little. "You have to promise to explain everything later." The Doctor tilted his head, paused. Then a wide grin spread across his lips.

"Right, you lot!" he called, spinning around again, the grin enormous and bright. "We're dealing with something rather unusual and extremely dangerous, so if you don't mind, I think that it'd be best if you remained here and let me and Doctor Watson do the greater part of this investigation. With my intelligence and his marksmanship we'll have this fixed in record time!"

The door suddenly banged open again, handle crashing into the wall with enough force to make it crack. Striding through the doorway was Sherlock Holmes, who took one look at the two doctors standing together and narrowed his eyes. The Doctor shook his head. "I keep getting interrupted, I hate being interrupted— doesn't anyone understand how important this is?" Holding up his identification again, he pointed it towards Sherlock with his eyebrows raised. "Right, if I might continue—!" The hand holding out the card was suddenly seized in an iron grip; Sherlock tugged it closer to his face, examining it, and scowled.

"Leave it to the Yard to be fooled by a bit of blank paper," he growled, and, grabbing the cuffs from Donovan, snapped them back around the Doctor's wrists.


	4. Chapter 4

**Hello all! Sorry I've taken so long to update— remember that reviews are food and encouragement and all so many good things come of them. Like inspiration!**

—

Several yelling matches and one whispered conversation with John later, the Doctor was re-released. Rubbing his wrists and giving Sherlock a resentful glare, he moved back to stand next to John. "As I was saying! The taikreng are fast-acting and growing, and a wrong move could be our last. Which is why I've been keeping them contained as best I can in here."

"There can't be parasites in those bodies," Sherlock said abruptly, scowling right back at the stranger. "Parasites live on the processes performed by live creatures. That's what it _means_ to be parasitic. This is a morgue, if you haven't noticed." A flash of annoyance crossed the Doctor's face.

"It's complicated," he bit out, turning away from Sherlock. "More complicated than I can explain now, seeing as this is an emergency—"

"I'm very clever, I'm sure I could understand if it _actually_ made any sense."

"Sherlock! Shut up!" John barked. His hands had balled into fists at his sides. The look Sherlock gave him was shocked. He tried to ignore the surprised expressions on the faces of the police, the hurt in his friend's eyes. "Look. We need him, he knows what he's talking about. Just listen."

"Actually, that's all for now!" The Doctor moved to the door, beckoning John to follow him. "We don't have much time so I'll just say this again: _Stay put._ Don't go in here unless you hear us screaming bloody murder, and even then, fight the impulse. Got it? Let's—"

"Hold on." Sherlock had crossed the room in a few long steps, eyes burning holes into the Doctor's, lips thin and white at the edges. "I'm coming too." He leaned forward slightly. "You know I'm smarter than them; whatever you did to that card— some sort of illusion or psychic trick— wasn't enough to trick me. Nor is it technology that would be carried by anyone civilian. Maybe not even human, though that hardly makes sense," he said, giving an obviously feigned huff of laughter. "I'm genius, an asset. I'm coming."

The Doctor straightened his shoulders, surveying the other man appraisingly. "So? I'm a genius myself. I'm very clever, much cleverer than you, and I don't much care for your patronization." There was a long pause. "I'm the one who knows what's going on here. Not you. Though, technically," he continued with a slight smile, turning toward John, "it was Doctor Watson who figured it out. Good on you for that, by the way, I should have told you back in the hall, but the circumstances were—" He pulled a face. "I knew you'd get it eventually."

Sherlock's eyes narrowed. "So if you don't want my help, why are you asking for _John's?_ He's not a part of this investigation."

"Since when?" the Doctor countered, placing his hands on his hips, watching the other man closely.

"He's not a detective, or a policeman. He's just my assistant." Behind Sherlock, John's expression twisted and immediately became blank. Before, he'd been introduced as a friend. What the hell had he done to deserve this? Thrown out one too many experiments? Forced the man to watch a particularly awful action movie? A sense of dread crept down through his body, a slow sickening in his gut. As if something important was slipping through his fingers. Which, John noticed, glancing at his left hand, were trembling. Clenching the offending appendage, he considered punching the arrogant bastard— but there was much more than his pride at stake here. They were losing time.

"If you're done with your pissing contest," he cut in, "I think the Doctor and I have something that we need to attend to." He knew the tension in his face and shoulders was all too visible. John could see a flicker of recognition in Sherlock's eyes and, hard on its heels, something like fear.

"Quite right!" The Doctor moved away from the two of them, rubbing his hands a little as he walked towards the double doors. "You can come along if you like Sherlock, but I wouldn't recommend it. It's not really your field of study, what we're dealing with." Sherlock gave an audible sniff, looking away from John.

"I assure you, I'm quite capable of taking care of myself."

"Right, of course, that's why you need an assistant," the Doctor said politely, turning to smile at the other man. John couldn't help the snort that burst out of him, though he immediately placed his fist over his mouth. The smile slid towards him, grew into a happy grin. "John? Ready?" Grinning back, he nodded. "See everyone in a few minutes, if we aren't killed in the meantime!"

—

They slammed the doors open, the Doctor pulling out his cylinder as they did so and buzzing the nearest vines. "Some explanation, now that we're out of the vicinity of people who would most likely have a conniption fit if they heard what I'm about to say: these are aliens, not just parasites, I'm an alien, not just a doctor, and this is sonic, not just a screwdriver." John stared at the object in his hand.

"That's a screwdriver? Why do you have a screwdriver?"

"Well," he said, shifting a bit uncomfortably in his jacket, "for… screwing things. And other things! it scans and— and opens cracks in time-space— it's a multitool!" He shook it in John's face. "It's very important, alright? Does a lot of complex stuff."

"Like acting like a dog-whistle for parasitic aliens," John said, the corner of his lips quirking as the Doctor huffed.

"Yes! Exactly! Very important!" The man straightened a bit. "Though it doesn't work on wood."

"You were giving an explanation," Sherlock said pointedly, expression stiff as he watched the pair of them.

"Right, yes—" Spinning on his heel, the Doctor directed his glare back at the busily moving creatures. "These are taikreng, an intergalactic and sometimes inter-dimensional species of nomadic parasites that feed on the consciousnesses of all bipedal creatures and use their bodies as their homes and eventual mating grounds, discarding them when they have outlived their usefulness and using them as a jumping point for other infection. Which means, as you pointed out earlier—" the Doctor moved forward and knelt by the vines "— that the bodies currently in this morgue are not dead."

Standing again, he moved down the hall, directing his sonic screwdriver this way and that. "They're both being kept alive and being drained by the taikreng, who have staged, quite nicely, a series of serial killings."

"Why?" John broke in, brow furrowed, bewilderment clearly written across his face. "I mean, what's the point of that?"

"Disguise!" The Doctor's statement was more like a crow, admiration tingeing his voice as he fired off another sonic blast. "They've been running for a while, this lot, and they know that people are looking for them, myself included. See, they usually have a pattern: they infect one person, get them sent to the hospital, and then proceed to infiltrate the entire facility, moving out from there. It's easier— they're capable of moving the body they're in to get at a new victim, but it takes a lot of effort. Why walk when you can simply build a neighborhood from rows of hospital beds?

"Only problem is that it's a calling card now." They were getting closer to the morgue now, the vines actually parting before them, sliding back to their source. The Doctor frowned at the doors, half ripped off their hinges by the force of the vines' pursuit. "An entire hospital in a coma? Pretty obvious sign of alien incursion."

"So they damaged their hosts to make it look like they'd been murdered, gestated in the morgue, and are spreading through the staff?" Sherlock breathed, watching the bizarre animals' retreat with fascination in his eyes. "Ingenious."

"Just buying themselves time," the Doctor said grimly. "They know they're not allowed to be here." Pushing open the door leading to the stairs, he led the way down into the morgue, John pulling out his gun as he followed close behind. The bloody mess that was the body of the guard lay oozing on the ground, the vines crimson where they had passed through the gore.

"Wait," Sherlock muttered, "the thing I didn't almost see—"

"Perception filter," John murmured back. Sherlock's head jerked towards him and he shrugged. "That's just what he said. Some sort of psychic block that keeps you from really _seeing_ them. I'm sure you'll understand it better than I do."

"Inevitably," Sherlock said, voice clipped. They stared at each other for a few seconds.

"Taikreng people of the planet Zolfate, you are guilty of violating Article 86 of the Shadow Proclamation— you cannot seed on a primitive planet not fully integrated into the galactic civilization." The Doctor's voice broke through the tense silence, strong and grave. As John's eyes turned back to the man, he saw in the Doctor's expression and posture a heavy resignation. His eyes, so full of life minutes before, were dead and weary, his shoulders bent with some horrible knowledge. An understanding of what was to come. "Furthermore, you are charged with the destruction of the civilizations of star system 78201 and the Trimaltiran colonies in sector 930, among other crimes."

"Is this to be our trial, Doctor?" The response did not seem to be aural, but rather sounded in John's mind. It was full of pain, the pain of centuries, of generations living on wounded pride and desperation. It had an edge to it that was wretchedly mocking. He hoped he only imagined that he saw the Doctor flinch. "If you were to as _just_ as you act, you would provide us with our assembly of equals."

"You know you have no support," the Doctor countered quietly. "You destroyed several well-established homespecies, that's much different than living on bipedal livestock. They won't accept your testimony."

"We've both committed genocide," the voice said, and John's eyes darted to the Doctor's face. "Why has no one put you on trial?"

"What I did was for the best."

"The best for who? The Saturynians, the Gelth. The Racnoss. So many dead. So many left without a home. Who bettered from your slaughter?" The voice grew deeper. "Certainly not your own race."

"It doesn't have to happen again." The Doctor took a step forward, his expression pleading, clearly hoping against hope. John tightened his grip on his gun as the vines pulled away, moving to slide around the Doctor, encircling him. Sherlock, however, scrutinized the man's face carefully, holding up a hand to John in warning. "I know you don't trust me," The Doctor continued, "I don't expect you to. But I also know the entirety of time and space, all that was or ever could be— there's more than one Zolfate. I can find you a home!"

"You do remember that these things have killed at least five people?" John's voice was low, guarded. He was out of his depth, but this wasn't right; those people had families, lives. "You can't just forget that! You can't let them walk away and _give them a home—_"

"This is not a matter of justice, Dr. Watson!" the Doctor shouted, barely turning to look at his companion. "It's much more complicated, and ancient, than you can ever imagine. This isn't about justice, there's nothing _just_ about the situation." Slowly, he looked back towards the vines. "This is about an old debt. And a lot of forgiveness."

"Forgiveness for whom?" Sherlock moved forward, peering into the Doctor's eyes, his own expression knowing, even dangerous. "Doctor, what have you done?" he asked quietly.

It happened so quickly, John wasn't even sure if he had truly seen it. His heart still sick with the implications of Sherlock's words, he had barely enough time to register the vines' change in direction and focus, bellowing some incoherent warning to his friend even as the creatures wrapped around him, pulling him back towards the guard's remains. Wild-eyed, he shot a look at the Doctor, who was already raising his screwdriver, yelling at the taikreng to put Sherlock down. "Convention 15 of the Shadow Proclamation, there is a cessation of hostilities in order to parley! This man is an observer, a bystander— you cannot touch him!" As the Doctor shouted commands, however, John could see the creatures gathering around Sherlock, who struggled and twisted their stalks in vain, desperation mounting as he realized he could not escape. John's pulse was pounding in his throat, nausea swelling as he raised his gun and realized he had no idea where to shoot. It was the pool again, but worse, much worse, because it was loud and fast and no one was _doing_ anything—

"Doctor!" he yelled in his fury, the word exploding from his lips. It seemed to bring the man to his senses and fill him with purpose.

"I demand that you release Sherlock Holmes of 221B Baker Street, planet Earth." A low chuckle resounded inside John's head, its depth almost painful, and the Doctor's expression became enraged. "You must release this human under Convention 15—"

"But these are not hostilities." The voice spoke softly, a single vine laden with spores rising up between the three of them. "This is not even a usurpation. How can it be, when they continue to live and walk throughout this planet? This is… cohabitation." The petals around the spores were peeling back, retreating. Revealing an inside multi-hued, the deepest part a dark burgundy, gradually blending with an emerald green, the spores on stems so delicate that they seemed like spindles. And John understood that this thing of beauty would have to die. Because between it and Sherlock, the sociopath was the heartless creature he minded least.

"Sherlock, duck!" he yelled, shooting the heart of the vine even as his friend jerked out of the way. The noise in his head was unbearable, an agonized scream that made John gasp for breath, stumbling forward blindly— he couldn't see, there was too much pain in his mind, in his bloody fingertips, he was choking on something, couldn't breathe— and he could hear the Doctor's screwdriver, and the cries only became higher, _louder_— "Ahhhh!" He dropped the gun, clutching at his head, and felt arms surround him on either side, pulling him up, out, away from the strong, thick vines that wrapped around his legs and his throat, choking him even more, away from the voice shrieking with fury.

"They're activating the others—!"

"What does that mean?" The two shouting, familiar voices cut through the noise, the deeper baritone somewhere near his head. Hearing it, John reached out, grabbed onto the person's arm, held it as tightly as he could. He was going to die, he could feel it moving inside him, coming for him—

"In here!"

"_What?_"

"Just get inside!"

And suddenly all was silent inside his head. Breathing shakily, John could hear footsteps thudding beneath him, carrying farther inside this sanctuary. "How does it work?" Sherlock's voice was close, very close, and sounded awestruck, but John couldn't open his eyes. The pain hadn't disappeared; if anything, it was growing. He barely held back a cry as they lay him down on something hard, cold, and metallic. The high-pitched whine of the sonic screwdriver passed over his face and the agony intensified, spiking suddenly and hard enough to make him scream. Every muscle convulsed; he could feel his back arch and fall as the spasms shot through him, his fists clenching, his nails biting into his palms and drawing blood. The world became a white haze of anguish, ending only when the sonic fell silent. He could hear the Doctor's breath catch, felt the man's callused hand press against his forehead. "What's wrong with him?" Sherlock's voice was shaking.

"There's a spore inside him." The Doctor stood and began pacing. "If we don't do something, and fast, John Watson will be the first casualty in this war."


	5. Chapter 5

"No." Someone wrapped John's fingers around something cold. A cylinder. He instinctively jerked away, but the person was insistent. "No, he shot the vine, that's not possible."

"When he shot the pod he scattered the spores." The Doctor's voice was very close to John's ear. It was his hand curling John's fingers around what had to be the screwdriver. "He told you to duck because he didn't want you breathing them in. He must have known there was a chance he'd get infected." Warm fingertips pressed against John's ribs, feeling the progress of the spore inside the ex-medic's lungs. "Oh, John Watson." The Doctor sounded very soft and very sad. "Whoever you can save, not just who you want to save. Including yourself."

"Shut up," Sherlock snapped, hard-soled shoes pacing across the metal floor, a faint sound John clung to. Sherlock was fine, he was walking and sounding angry and exasperated. That was worth something. "Just be quiet, don't even think, you think _very_ loudly— we have to come up with something to stop them, reverse the effects. How long do we have?"

"I've given him my screwdriver; I put it on its lowest setting, with a few modifications. It won't hurt John, but it also won't stop the spores. It'll slow them, though, so I'd say we have—" John felt one of the Doctor's hands lift from his torso, imagined him glancing at a watch, or his wrist— "two hours? An hour and a half?"

"Not enough time." Sherlock was muttering under his breath, his pacing faster and faster. John forced his eyes open slightly and watched the other man place his palms together beneath his chin, thinking, thinking, thinking. The Doctor's hands never stopped moving, pushing against John's temples, making sure nothing had started budding or growing inside him. "That's not enough time, it'll start spreading as soon as it can and there's no knowing what sort of damage it could do—" Agitation was showing on Sherlock's face. Frustration and rage. "Why the _hell_ did he do something like that?"

"Because he's not your assistant," the Doctor said slowly, standing. "Because there are people you wish had never met you, and he's one of them. Because when you're around, people want to impress you, and that makes you dangerous." John's sight was fading, but he could see Sherlock's gaze fixed on the Doctor's face. "And because you need him."

"You know nothing about me."

"I know enough to want to _hit_ you," the Doctor continued, in a slightly louder voice. "He does all that for you and you call him your assistant? No wonder his limp's acting up!"

"How do you know about that?" Sherlock's voice was shaking again, but it sounded more like barely restrained fury.

"How do you not? the tremor in his hand was more like a _quake_ back in the lobby—"

"_Shut up._"

Silence descended between the pair of them. In the tense, angry pause, John decided he needed to intervene and began maneuvering himself back onto his elbows, still clutching the screwdriver. The Doctor was back at his side in seconds, helping him sit up and lean against a rail of some sort. He opened his eyes slowly, taking in his surroundings even more sluggishly. He was in a… room. Of sorts. It was unlike any room he'd ever seen, a lush golden-red, with a circular type of tower in the center, and another, larger circle of bizarre levers and buttons around it. There were hexagons cut into the walls, and he was leaning against strange metal framework, head lolling against the crossbar as he looked at the curving metal staircase and the cushy looking chair on the other side. The entire place seemed to glow and groan with life. John shifted slightly to look at the Doctor. "…Alien, hmm?" The man simply grinned.

"I'm guessing I'm dying?" John continued as casually as possible. "Unless you two are planning on bickering loudly once every hour and I should just get used to this."

"You'd hardly have long to get used to it," Sherlock growled, "You only have two hours to live. At most." John frowned at his friend, It was a bloody joke, but the prat wasn't in the mood to laugh at himself. He began thinking, hard, about all he knew about parasites and killing them. Removing the spore wasn't possible and wouldn't do very much good.

"So, guns— a no go." The Doctor's grin flitted across his face again.

"Like I said, not terribly effective when you need them. And I'm not that keen on setting you on fire, though that would definitely kill them."

"Some sort of antibody then? No, it's fungus-like— ah!" John managed to gasp, pain contorting his features as he felt something reach out, spreading through the lower part of his lungs. "There are certain plants that we have people eat when they've been infested; they reboot the immune system and attack the organism—" It was suddenly much harder to breathe. The Doctor, however, gave a cry of happiness and pressed a kiss to John's forehead.

"Yes, of course, _yes_, we've been panicking instead of really considering all our options— Sherlock, go out, get the others out of the building, I'll rummage through the sick bay, I have specimens from all different galaxies, I'm sure I can find something that the taikreng'll have an averse reaction too, like a parasite allergy, or, rather, an allergy for parasites!" John acknowledged him with a smile, but the lack of oxygen was making him slip away, try as he might to stay awake. He could see that the Doctor was up and dashing to the staircase, pulling off his tweed jacket as he did and snapping his suspenders as he turned to look at Sherlock. "You haven't moved! Go, get a move on!"

"No."

The Doctor's smile slid from his face, and John fought desperately to remain conscious. What was Sherlock playing at? "Mr. Holmes, the rest of the Met's out there. I'm not definite about the taikreng's plan of action, but if it's what I think it is— and it usually is— then we're all in for a lot of very nasty fun." He twitched awkwardly. "Not like that."

"I'm not leaving."

"The fate of the human race is in your hands!" The Doctor tripped back down the stairs, eyes fixed on Sherlock's. The detective scowled darkly, stepping forward, suddenly making their conversation quiet, private. Impossible for John, who was barely concentrating anyway, to hear. "This is where you save the world," the Doctor suggested, tilting his head towards the door.

"The world can hang," Sherlock growled, glaring back at the Doctor. "John's sick and _I'm_ _not leaving_."

Expressions flit like moths across the Doctor's face, settling on something akin to relief, mixed with recognition. "That's very human of you, Mr. Holmes," he stated quietly. "–but I'm afraid you're needed elsewhere." A smile broke through his contemplation. "John will understand."

—

When he woke later, it was to the smell of tea.

The Doctor was pottering about, when he wasn't twirling and humming and throwing things that looked like full beakers into the air. "Hello! Conscious again, then?" he said cheerfully, whisking something awful-smelling in a what looked like a pot hooked up to a miniature electron collider. "I'd tell you what I was doing, but I don't think you'd want to drink this then, and it's very important that you do." John considered him silently for a few seconds, before forcing enough air into his agonized lungs to speak.

"…What are you doing?"

"Making tea!" the Doctor cut in, almost as soon as the words were out of his mouth. The corner of John's lips quirked.

"Are you lying?"

"Only somewhat!" the Doctor laughed, throwing something that looked horribly like a spiny water balloon into the pot. "There's definitely some Earl Grey in here— tea really does help all things, it saved my life once, maybe more than once— you English got that part of life down to a science. Tea science, that sounds like so much _fun_; maybe it'd be a quantum mechanics study: how much tea can you drink before you start seeing the waves in the cup as _particles?_ But yes, there's a lot more in here that you don't want know about. Liiiiike the skin of the Yerolnckzer! And a particular fluid that isn't good to mention in polite company, ever, partly because it's illegal but mostly because it's disgusting." He put the lid on the pot, _latched it_, and pressed the button on the electron collider, causing the thing to spin very, very fast. John glanced to the Doctor, concerned, and the other man grinned wildly, running away from the whirling kitchenware as fast as his long legs could take him. A second later, the pot went flying and slammed into the opposite wall.

The collider went "ding!"

"Nothing like a piece of outdated technology to make a delicious tea-medicinal-type-stew-thing!" He bounded to the place where the pot had landed and, hissing as it burned his fingers, carried it back over. John watched him without much assurance in his eyes. "John, this was your idea— you have to trust me."

"How did you know about my hand?" John said abruptly, surprising even himself. "And my limp." The Doctor paused, becoming serious.

"I live right under you, John. I could hear you go both up and down the stairs for several days. It wasn't until after I heard you two fighting that I ever heard the tread of your footsteps vary. And then I saw you in the morgue that day, and you looked—" He stopped, seeing John's expression. "It was only natural to assume that if your limp was psychosomatic, and was affected by the argument, that your nervous tremor had a similar beginning, and trigger. The war— and Sherlock."

John was silent for a few seconds, looking down at his hand. "And I'm guessing that when you saw me in the morgue, you could tell from my posture and tan lines that I had been a shoulder, and figured out that I was working with police by seeing how I reacted to you breaking in." The Doctor looked slightly guilty.

"Er, no." He gave a hesitant smile. "I talked to Mrs. Hudson." John stared at him. "She told me everything about you two. And gave me tea." The Doctor paused. "And jammy dodgers." They both started to smile. "Which isn't to say that I couldn't have worked it all out like that."

"So why didn't you?" John's smile was growing inexorably wider. The other man shrugged.

"Not as much fun!" He couldn't help it: the giggles that burst from his lips hurt his lungs awfully, but John just couldn't stop laughing. Of course, he thought, another chuckle escaping him, an alien doctor that was trying to feed him strangely concocted medicine inside his spaceship would think that having tea and jammy dodgers with his landlady was fun. _Fun._

"You— you have an odd idea of fun—!" he choked out, holding his stomach as laughter convulsed through him. The Doctor cocked an eyebrow and grinned back at him, unlatching the pot.

"You haven't even seen the best bits!"

—

Sherlock ran back through the corridors, armed with John's apparently useless firearm and a furious need to hurry, get back to the— blue police box… as soon as possible. He was also cursing the Doctor for existing, for dragging John into a situation that they clearly could not handle and that was not a part of their world, but that wouldn't help. Becoming angry at the man who had possibly just gotten his only friend killed would not help matters. Though it would keep the guilt from rising inside him like a wave, swallowing him and making him sick at heart.

He rounded a corner and ran almost directly into Lestrade, who shouted and jumped back. "Sherlock! Where have you been? Where's John, we heard shots and screaming, I sent people in to look for you!" Inwardly, Sherlock began cursing every busybody, idiot policeman who entered the building as well, racking up a grand total of fifteen people he would surely murder with his own hands if John died that night.

"I've been told to get you out of the building," he nearly yelled, already realizing that this rescue mission of his was futile; they'd all headed for the mortuary. "The taikreng are on the move, and if anyone goes near them—"

A broken, horrifying chorus of shrieks cut through his sentence. Sherlock and Lestrade dashed down the corridor, following the sound of something sure to be sickening, screeching to a halt in front of the morgue. Lestrade shouted something incoherent and Sherlock, for once, was speechless. The corpses were moving— an army of murdered men and women, vines sprouting from their collapsing, mutilated bodies, were climbing from their drawers and blowing spores in the faces of the officers who sank to the ground screaming. Dashing out of the mortuary came Anderson, panting and whining pathetically as he tried to slam the door, almost locking Donovan on the other side. "Zombies!" he yelled. "The living dead!"

"No," Sherlock said quietly. "The taikreng's army."


End file.
